Abstract MP68: Effects of Macronutrients on Serum Short Chain Fatty Acids (SCFA): Results From the Optimal Macro-Nutrient Intake to Prevent Heart Disease (OmniHeart) Trial

Abstract

Introduction: Emerging evidence links greater concentrations of serum SCFA, derived from microbial fermentation of indigestible fiber in the colon, with better cardiometabolic health. The OmniHeart trial tested the effects of 3 diets that differed in % kcal of carbohydrate, protein, and unsaturated fat; each diet was high in fiber (~30g/day) and isocaloric. Hypothesis: All 3 diets, being high in fiber, would increase SCFAs, but there will be differences between diets. Methods: The OmniHeart trial is a randomized crossover trial that enrolled 158 men and women, aged 30 years or older, with systolic blood pressure 120–159 mm Hg, diastolic blood pressure < 100 mm Hg. Participants consumed each of 3 different isocaloric diets for 6 weeks in random order: a carbohydrate (CARB)-rich diet (similar to DASH); a protein (PROT)-rich diet with protein predominantly from plant sources; and a diet rich in monounsaturated fat (UNSAT). Fasting serum was collected from participants at baseline, while they consumed their own diet, and at the end of each diet intervention period. SCFAs were measured in stored serum with LC-MS/MS (Metabolon Method TAM148)and normalized by log transformation. We fitted a linear regression model using generalized estimating equations to examine mean change in log-transformed SCFAs from baseline in each diet and between diets. Results: Compared to baseline diet, all 3 diets increased acetic acid; CARB and UNSAT diets decreased propionic acid; and the PROT diet increased butyric acid ( Figure 1, top panels ). PROT increased acetic acid more than CARB, but no differently than UNSAT. PROT increased propionic acid compared to both CARB and UNSAT ( Figure 1, bottom panels ). Conclusion: All 3 high-fiber OmniHeart diets affected microbiota-derived serum SCFA concentrations with some notable differences between diets. Future research is needed to determine whether changes in SCFA mediate the relationship of dietary change and cardiometabolic disease risk factors.